I saw the Fluval U1 and U2 internal filters at the store the other day, and would like to use one of those to reduce noise. Has anyone had any experience with these? For a 10g tank, which one would be better? I will probably use the top spout output with aeration, so it creates some surface agitation, or would using an airstone's bubbles would be enough agitation? I know the U2 will take up more room in the tank, so am considering using the U1. However, it does not have a carbon filter option with it, and am wondering if it would be better to use the U2 to at least have that option.